Evans D L, Dive C
CRC Molecular and Cellular Pharmacology Group, School of Biological Sciences, Manchester University, England.
Cancer Res. 1993 May 1;53(9):2133-9.
A 2-h exposure of JB1 rat hepatoma cells in late log phase of growth to 50 microM cis-diamminedichloroplatinum (II) (cisplatin) resulted in the asynchronous detachment of cells from the monolayer over 4 days. Detached but not monolayer cells exhibited condensed chromatin and DNA fragmentation, which is indicative of endonuclease activation, the hallmarks of apoptosis in epithelial cells. The number of cisplatin-treated cells identified as apoptotic at any one time was never > 1% of the total cell number present on addition of drug. Two days after drug addition there was a decrease from 85% to 29% cells in G1 phase of the cell cycle, cells in S phase increased from 9% to 18%, and cells in G2/M phase increased from 6% to 51% with respect to untreated cells. Previous studies by Eastman and colleagues demonstrated that cisplatin-induced apoptosis of Chinese hamster ovary cells occurred in the G2 phase of the cell cycle [A. Eastman, Cancer Cells (Cold Spring Harbor), 2: 275-280, 1990]. Continuous exposure of JB1 cells to cycloheximide (1 microM) during and after exposure to cisplatin prevented both drug-induced changes in cell cycle distribution and the engagement of apoptosis. Freshly isolated immature rat thymocytes are known to be exquisitely sensitive to the induction of apoptosis by multiple stimuli including dexamethasone, etoposide, and irradiation. However, no significant increase in the amount of apoptosis above control levels was observed up to 36 h after a 2-h exposure to 50 microM cisplatin. JB1 cells have a doubling time of 24 h, whereas > 90% of immature rat thymocytes are noncycling. The data presented here provide indirect evidence that initiation of cisplatin-induced apoptosis may need to be coupled to a cell cycle-mediated event.
将处于生长对数后期的 JB1 大鼠肝癌细胞暴露于 50 微摩尔顺二氯二氨铂（II）（顺铂）2 小时，导致细胞在 4 天内从单层中异步脱离。脱离的细胞而非单层细胞表现出染色质浓缩和 DNA 片段化，这表明内切核酸酶被激活，这是上皮细胞凋亡的标志。在添加药物时，任何时候被鉴定为凋亡的顺铂处理细胞数量从未超过总细胞数的 1%。添加药物两天后，与未处理细胞相比，处于细胞周期 G1 期的细胞从 85%降至 29%，处于 S 期的细胞从 9%增加到 18%，处于 G2/M 期的细胞从 6%增加到 51%。伊斯特曼及其同事之前的研究表明，顺铂诱导的中国仓鼠卵巢细胞凋亡发生在细胞周期的 G2 期[A. 伊斯特曼，《癌细胞》（冷泉港），2: 275 - 280，1990]。在暴露于顺铂期间及之后，将 JB1 细胞持续暴露于环己酰亚胺（1 微摩尔）可防止药物诱导的细胞周期分布变化和凋亡的发生。已知新鲜分离的未成熟大鼠胸腺细胞对多种刺激（包括地塞米松、依托泊苷和辐射）诱导的凋亡极为敏感。然而，在暴露于 50 微摩尔顺铂 2 小时后长达 36 小时，未观察到凋亡量比对照水平有显著增加。JB1 细胞的倍增时间为 24 小时，而超过 90%的未成熟大鼠胸腺细胞不进行细胞周期循环。此处呈现的数据提供了间接证据，表明顺铂诱导凋亡的起始可能需要与细胞周期介导的事件相关联。
